Left ventricular sytolic function is an important determinant of long-term prognosis in patients with aortic regurgitation (AR). We studied 130 patients with AR to correlate assessment of LV systolic function by redionuclide angiography, (LV ejection fraction) and echocardiography (LV fractional shortening and systolic dimension). Radionuclide and echo assessment of LV systolic function correlated well at rest. In addition LV ejection fraction during exercise was also related to resting echo LV systolic dimension. During serial studies, echo LV systolic dimension was a stronger predictor of deterioration in resting LV function than was redionuclide ejection fraction. Thus, echo data provides important additional information to radionuclide assessment of LV function in the management of patients with AR.